Although tamper evident shrouds have been previously proposed, they have not found wide application in the packaging industry because of their inherent complexity of design, difficulty of manufacturing, and high cost of production. The high cost of modifying or producing new containers suitable for use in combination with these known closure devices has also presented a barrier to their widespread acceptance.
While known tamper evident shrouds are designed to reveal unintentional or unauthorized removal of the closure from the container, they are not generally adapted to reveal unauthorized use of a pump or a pop-up squirting nozzle incorporated into the closure, where such device can be used without removal of the closure from the container.
One known form of tamper evident container shroud is described in U.S. Pat. No. 3,037,672 (Gach). However, the shroud disclosed in this patent is usable only with aerosol cans or other metal containers which provide a sharp shoulder or other projection of generally rectangular or square cross-section to be gripped by the engaging rim of the shroud, which rim itself is of generally rectangular cross-section with a flat upper engaging surface oriented parallel to the interacting shoulder of the container in the engaged configuration. Such a shroud is not adaptable to modern plastic or glass containers formed, for example, by blow moulding techniques, which lack such sharp shoulders. Moreover, the Gach shroud can only be moulded, because of the geometry of its engaging rim, with mould die members capable of a side action, in addition to the axial movement of the male and female die members. This increases the costs of moulding such a shroud to unacceptable levels.
Another known form of tamper evident container shroud is described in U.S. Pat. No. 3,474,930 (Lerner). This shroud is, like the Gach shroud, only of practical utility when used with metal cans or other containers having a sharp shoulder or other projection of generally rectangular or square cross-section to be gripped by the engaging rim of the shroud, which rim itself has a planar upper engaging surface oriented generally parallel to the interacting shoulder of the container in the engaged configuration, such that minimal frictional interference between the shoulder and the rim is sufficient to effectively hold the shroud on the container. When used with the previously described modern forms of moulded glass or plastic containers having shoulders or projections of more rounded geometry, the geometry of the Lerner shroud fails to provide sufficient frictional interference to prevent undetected removal. Moreover, if the degree of interference between the shoulder and the rim is increased by increasing the physical overlap of these two components, the resilience of the shroud material will be insufficient to allow, on installation of the shroud, movement of the rim past the shoulder without causing fracturing of the tamper evident means. Additionally, the Lerner shroud illustrated in U.S. Pat. No. 3,474,930, cannot, in view of the generally planar perpendicular geometry of the shroud rim, be made without the use of die elements capable of a side action moulding operation.
It is, therefore, an object of the present invention to provide a simple and inexpensive tamper evident container shroud which can be made in a simple moulding operation by moving the male and female die members axially without side action of the die members. This eliminates the difficulty and expense of moulding which is inherent in a side action type of moulding.
Another object of this invention is to provide a tamper evident shroud which can be used in combination with pre-existing moulded glass or plastic containers with only minor inexpensive modifications to the moulds for these containers. Typically, the neck section of such existing containers can be modified by providing a smooth groove around the mouth of the container so as to present a peripheral ridge for engagement by the shroud in a manner more fully described below.
Another object of this invention is to provide a shroud constructed of an ultra high-flow low-density polyethylene resin, which shroud, when heated, overcomes the resiliency problems encountered in the installation of previously known designs of tamper evident container shrouds.
It is a further object of the invention to provide a container shroud for use with moulded plastic or glass containers which will, when unintentional or unauthorized removal of the shroud is attempted, provide clear visual evidence of such tampering. Similarly, an attempt to remove the container closure without removal of the shroud will provide visual evidence of such an attempt.
A still further object of a preferred embodiment of the invention is to provide a container shroud for use with moulded plastic or glass containers which shroud incorporates a tear-off strip that can be peeled cleanly from the shroud along a notch-line of weakness to facilitate opening of the container by the intended consumer, the remaining cup-shaped portion of the shroud being replaceable over the closure, and being dimensioned to serve as a dust cover and/or measuring cup for the container contents.
A tamper evident container shroud in accordance with the invention is designed for use with a moulded glass or plastic container having a mouth with an outwardly projecting peripheral ridge and a closure for the mouth. The shroud is moulded of ultra high-flow low-density polyethylene resin and can, upon heating, be pushed onto the container over the closure to encase the closure, the shroud having a cup-shaped body portion and a resilient rim portion of generally circular cross-sections which can be pushed over the peripheral ridge of the container with the body portion free of contact with the closure located within the shroud, the shroud having a relatively weak portion between its body and rim portions, the resistance of the weak portion to tearing being less than the resistance of the rim portion to being pulled back, after cooling, over the peripheral ridge of the container, whereby access to the closure cannot be had without visibly tearing the weak portion of the shroud.
The invention further relates to, in combination, a moulded plastic or glass container having a mouth with an outwardly protruding peripheral ridge, a closure for the mouth and a shroud having a cup-shaped body portion within which the closure is encased, the shroud having an outwardly stepped rim portion having an inwardly protruding peripheral ridge of generally circular cross-section extending under the ridge of the container and holding the shroud on the container with the cup-shaped portion free of contact with the closure, the shroud being moulded of ultra high-flow low-density polyethylene resin, with a notch-line of weakness between the rim portion and cup-shaped portion, the resistance of the line of weakness to tearing being less than the resistance of the ridge of the rim portion to being pulled over the ridge of the container if the cup-shaped portion is pulled to expose the closure whereby access to the closure cannot be had without visibly tearing the shroud at the line of weakness, thereby providing evidence of tampering. The rim portion also constitutes a tear-off strip that can be peeled off the cup-shaped body portion along the notch-line of weakness, whereby the cup-shaped body portion can serve as a measuring cup. Where the cup-shaped body portion of the shroud is impervious to dust, and the rim portion is removed as aforesaid, the cup-shaped body portion can also serve as a dust cover.
Furthermore, the rim portion of the shroud may be fitted with an external flexible tab having a free end connected by a rupturable web to the rim portion, the tab having an end fixed to the rim portion adjacent a transverse notch-line of weakness of the rim portion, the inwardly protruding peripheral ridge of the rim portion being interrupted at the transverse notch-line to facilitate rupture of the rim portion along the notch-line when the tab is pulled to peel the rim portion off the cup-shaped body portion.